1. Field of Invention
My invention relates generally to gimbaled weapon stations (GWS) that provide sighting, fire control and a weapon cradle in a self-contained system and to methods for using a GWS. In particular, the gimbaled weapon station of my invention allows a weapon cradle and a sighting system to move together in azimuth, but each can be elevated completely independently of each other. This allows for continuous target tracking and sighting regardless of the super-elevation needed for the weapon to achieve the correct ballistic trajectory. My weapon station can also be stabilized and operated remotely.
2. Description of the Prior Art
Target tracking and weapon control systems are known. For example, on ships, a single weapon sight that can move in both azimuth and elevation can control and direct fire of several large weapons. These large weapons can also move in both azimuth and elevation in response to signals received from a fire control computer, which receives input from the separately controlled weapon sight. For smaller weapons, such as machine guns, it is known to combine the weapon sight and cradle on a single platform typically with the sight mounted directly on the weapon or the weapon cradle, but in either case there is only a single elevation axis. One such small weapon control system is disclosed in U.S. Pat. No. 5,949,015, which provides for a weapon mount and sighting system on a single gimbaled mount. The system can be operated by remote control and includes gyro stabilization. Such systems, however, suffer from the drawback that both the gun sight and the weapon share a common elevation mechanism. In other words, as the operator moves the gun sight to track a target in either azimuth or elevation the weapon must necessarily follow. Accordingly, if the operator raises the gun sight in elevation to track the target the weapon will also raise in elevation because there is only a single elevation mechanism to raise both the sight and the weapon. In these prior art systems, it is typical that the gun point and the aiming system (gun sight combined with basic fire control) are directed at the same target coordinates. Various sensors are typically used for the aiming systems; for example, visible and infrared imaging devices to view the target and a laser range finder to determine distance to the target. However, in situations referred to as super-elevation, where the weapon must be elevated to a greater angle than the target line of sight in order to launch the projectile to the hit the target over a long distance, the sighting or aiming system no longer views the target since the aim point of the gun no longer includes the target in the field of view.
In situations where a fire control computer can correct for ballistic trajectory (i.e., it can automatically raise the weapon to a super-elevation position to ensure the projectile impacts the target) a serious problem arises when there is only one elevation axis. When the fire control computer super-elevates the weapon, the sight must also increase in equal elevation. This causes the user to completely lose view of the target in the sight. If the user tries to override the fire control computer and lower the sight to regain view of the target the weapon will also be lowered causing a fired projectile to fall short of the designated target.
The art has recognized this serious problem and has attempted to provide a solution. For example, some weapon systems provide an offset mechanism. One such mechanism counter rotates the gun sight from the gun by an amount needed to bring the target back into the field of view of the sight. The disadvantage of this system is that it can introduce errors in the aiming accuracy because of the added complexity and mass of the additional counter rotation system components, which are placed on the single weapon elevation axis. This added complexity and mass must be added to the sole elevation mechanism, which greatly increases the chances for error in aiming the gun during super elevation. Another disadvantage is that counter rotation has a very limited range of movement and it can also introduce target image blur as the offset between the gun and sight is being established. Prior art systems can have offset mechanisms that cause either small mechanical elevation changes of the gun, the sight, or cause an electronic repositioning of the sight reticle in the sight display. U.S. Pat. Nos. 5,456,157, 5,171,933, and 4,760,770 each disclose variations in the type of offset mechanism utilized by the weapon system. For example, in the '933 patent the gun is offset by several servo motors to achieve super-elevation once target acquisition is acquired by the user. In the '157 patent a computer generated offset of the sight reticle is used to correct the gun aim point for super-elevation targeting requirements. In each of these known offset systems, however, the amount of offset possible is very limited, which of course drastically limits target range capability. A need therefore exists to provide a gimbaled weapon system (GWS) that avoids these problems and that allows mechanical elevation of the sighting system independent of weapon elevation, while allowing the weapon to achieve a super-elevation position to ensure target hit accuracy.
Accordingly, one object of my invention is to provide a self contained GWS that has two separate elevation means, one for a sighting system and one for a weapon cradle, where the cradle can hold a variety of different weapons. This system provides for totally independent elevation axes and associated control and drive mechanisms.
Another object of my invention is to provide a GWS that eliminates the need for an offset mechanism when super-elevation is needed for correct ballistic trajectory. This is accomplished by providing full elevation axes for both the weapon cradle and sighting system.
A further object is to provide a GWS where the dual elevation axes are stabilized independently or in common. Stabilization is very beneficial when large mass weapons are used with my GWS or when the GWS is used on a moving platform, such as a tank, troop carrier or other wheeled vehicle or boat deck.
Yet another object of my invention is to provide a control algorithm to coordinate the movement of the two independent elevation axes so that the user can continuously view and track a target without interruption and which will allow the weapon cradle (and the installed weapon) to achieve a correct super-elevation position independent of the actual elevation of the sighting system.
Other objects will be recognized upon reading the following disclosure in conjunction with the accompanying figures.